Sleeping for under seven hours a night greatly raises the risk of catching a cold, US research has suggested.Interesting, but not too surprising. After all, when we're sick, isn't sleeping all we want to do? And isn't that our bodies' way of telling us that that's what they need in order to heal?
A team from Carnegie Mellon University found the risk was trebled compared with those who slept for eight hours or more a night.
It is thought that a lack of sleep impairs the immune system and the body's ability to fight off the viruses that cause colds and flu.
Previous research has suggested that people who sleep seven to eight hours a night have the lowest rates of heart disease.
However, there has been little direct evidence that getting a good night's sleep can help ward off a cold.
The less an individual slept, the more likely they were to develop a cold.
The quality of sleep also appeared to be important. Volunteers who spent less than 92% of their time in bed asleep were five-and-a-half times more likely to become ill than those who were asleep for at least 98% of their time in bed.
The researchers believe that lack of good quality sleep disturbs regulation of key chemicals produced by the immune system to fight infection.
Professor Ron Eccles, director of the Common Cold Centre at the University of Cardiff, said sleep and the immune system were closely linked.
He said: "The immune system may control the sleep-wake pattern and lack of sleep or sleep disturbance may depress the immune response to infection.
"I do believe there is enough information on this to indicate that lack of sleep or sleep disturbance will reduce our resistance to infections such as colds and flu."
So go to bed early tonight. Or sleep late tomorrow, I guess.